MAHOUT-681 :Implement T-gate (π/8 gate) across all backends #693
Conversation
- Add apply_t_gate() method to QuMat class with validation - Implement T-gate support in Qiskit, Cirq, and Amazon Braket backends - Restore T-gate documentation in basic_gates.md to match implementation Fixes apache#681
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cc @guan404ming @rawkintrevo is it correct what r ur opinions on it |
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Pull request overview
This PR implements the T-gate (π/8 gate) across all quantum computing backends (Qiskit, Cirq, Amazon Braket) to resolve an inconsistency where the documentation claimed T-gate support existed but no implementation was present in the codebase. The T-gate is essential for universal quantum computation when combined with Hadamard and CNOT gates.
Key Changes
- Added
apply_t_gate()method to the main QuMat API class with comprehensive docstring - Implemented backend-specific T-gate functions for Qiskit, Cirq, and Amazon Braket
- Updated documentation to reflect that T-gate is now fully implemented (removed "New Addition" label)
Reviewed changes
Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.
Show a summary per file
| File | Description |
|---|---|
| qumat/qumat.py | Added apply_t_gate method to QuMat class with validation and backend delegation |
| qumat/qiskit_backend.py | Implemented T-gate using Qiskit's native t() method |
| qumat/cirq_backend.py | Implemented T-gate using Cirq's T gate on LineQubit |
| qumat/amazon_braket_backend.py | Implemented T-gate using Amazon Braket's t() method |
| docs/basic_gates.md | Removed "(New Addition)" label from T-Gate section header |
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qumat/qumat.py
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| Applies a π/4 phase shift to the qubit. Essential for universal | ||
| quantum computation when combined with Hadamard and CNOT gates. |
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The docstring incorrectly states "Applies a π/4 phase shift" but the T-gate actually applies a π/4 phase to the |1⟩ state, not a π/4 phase shift to the overall state. More accurately, the T-gate can be described as applying a relative phase of π/4 or introducing a phase of e^(iπ/4) = e^(i45°) to the |1⟩ state. The phase shift terminology is potentially misleading.
| Applies a π/4 phase shift to the qubit. Essential for universal | |
| quantum computation when combined with Hadamard and CNOT gates. | |
| Applies a relative phase of π/4 (i.e., multiplies the |1⟩ state by e^(iπ/4)). | |
| Essential for universal quantum computation when combined with Hadamard and CNOT gates. |
| def apply_t_gate(self, qubit_index): | ||
| """Apply a T-gate (π/8 gate) to the specified qubit. | ||
| Applies a π/4 phase shift to the qubit. Essential for universal | ||
| quantum computation when combined with Hadamard and CNOT gates. | ||
| :param qubit_index: Index of the qubit. | ||
| :type qubit_index: int | ||
| :raises RuntimeError: If the circuit has not been initialized. | ||
| """ | ||
| self._ensure_circuit_initialized() | ||
| self._validate_qubit_index(qubit_index) | ||
| self.backend_module.apply_t_gate(self.circuit, qubit_index) |
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The newly added apply_t_gate method lacks test coverage. The test file testing/test_single_qubit_gates.py has comprehensive test classes for all other single-qubit gates (TestPauliXGate, TestPauliYGate, TestPauliZGate, TestHadamardGate, TestNOTGate, TestUGate), but no TestTGate class exists. Consider adding a test class similar to the existing ones that verifies:
- T-gate state transitions (e.g., T|0⟩ = |0⟩, T|1⟩ applies phase)
- T-gate phase accumulation (T^8 = I)
- Cross-backend consistency
- Combination with Hadamard to verify phase effect
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cc @guan404ming |
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Need to resolve the pre-commit error. |
issues resolved |
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@guan404ming do you want to take another look? |
3 participants
Purpose of PR
Implements the T-gate (π/8 gate) across all backends to resolve the discrepancy where the documentation claimed T-gate support was "Added" but no implementation existed in the codebase.
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